This disclosure relates to a vaporized fuel processing apparatus including a canister equipped with an adsorbent capable of adsorbing vaporized fuel generated in a fuel tank, and a closing valve provided in a vapor path connecting the canister and the fuel tank to each other.
A pertinent conventional vaporized fuel processing apparatus is disclosed in Japanese Laid-Open Patent Publication No. 2013-113198. The vaporized fuel processing apparatus according to Japanese Laid-Open Patent Publication No. 2013-113198 is equipped with a canister housing an adsorbent capable of adsorbing vaporized fuel generated in a fuel tank, a closing valve provided in a vapor path connecting the canister and the fuel tank to each other, and a purge path connecting the canister and an intake path of an internal combustion engine (engine). In the vaporized fuel processing apparatus, when the engine is started and a predetermined purge condition holds good, negative pressure generated in the engine acts on the interior of the canister via the purge path in a state where the interior of the canister is open to the atmosphere. As a result, air flows into the canister such that the vaporized fuel adsorbed on the adsorbent is purged and then the purged vaporized fuel is guided to the engine via the purge path. Further, during such purge operation of the canister, the closing valve in the vapor path is opened to perform depressurization control of the fuel tank. In the depressurization control of the fuel tank, a valve opening duty of the closing valve is set based on the inner pressure of the fuel tank (tank inner pressure) and the amount of gas flowing through the purge path (purge flow amount).
In the vaporized fuel processing apparatus, if a tank inner pressure sensor functions abnormally (e.g., failure), the valve opening duty of the closing valve cannot be set, and the depressurization control of the fuel tank is not possible. Accordingly, there has been a need for improved vaporized fuel processing apparatuses.